Effect of transient chemically induced colitis on the visceromotor response to mechanical colorectal distension

Background Acute mucosal inflammation may initiate alterations of visceral sensory function. However, experimental studies on the potential effects of a transient inflammation on visceral sensitivity are lacking. Methods We performed colorectal distensions with a barostat device in fasted, conscious, male Lewis rats (n = 20) and assessed the nociceptive response (visceromotor response; VMR) to tonic colorectal distension (CRD) (60 mmHg/3 min) by abdominal-wall electromyography. Measurements were taken before and 3, 5 and 14 days after induction of a transient and self-limiting colitis by instillation of trinitrobenzenesulphonic acid (TNB)/ethanol (or saline as control). Tissue samples from paired controls were obtained to assess histological tissue alterations. Results TNB/ethanol but not saline induced an acute colitis, with most severe histological lesions occurring 5 days after instillation. After 14 days, there was no histological evidence for persisting mucosal alterations. Five days after induction of TNB/ethanol colitis, the VMR to CRD reached a transient increase (P < 0.05 It. baseline), which returned to baseline levels by day 14. In control experiments (rectal saline instillation), the VMR to CRD decreased significantly compared with baseline values (P < 0.05). Conclusion Following an acute colitis due to single colorectal instillation of TNB/ethanol, histological changes are associated with an enhanced nociceptive response to CRD.